Production of light hydrocarbon gases by hydrocracking high boiling hydrocarbons



y 8, 1968 w. BUSS 3,385,782

PRODUCTION OF LIGHT HYDROCARBON GASES BY HYDROCRACKING HIGH BOILINGHYDROCARBONS Filed May 6, 1966 COMPARISON CATALYST CURVE A Z 9 TOTAL 2CONVERSOION TO 900 F. l.| J ,cuRvE E z 0 8 I /-CURVE F o 2 CURVE B 6 a:Pd ALUMINOSILICATE E CATALYST COMPARISON CATALYST 2o- I c4 -cuRvE c CURVE o o l l 1 I I 760 no aoo 820 4540 see 680 TEMPERATURE INVENTORWALDEEN C. BUSS TORNES United States Patent 3,385,782 PRODUCTION OFLIGHT HYDROCARBON GASES BY HYDRUCRACKIN G HIGH BOIL- ING HYDROCAONSWaldeen C. Buss, Richmond, Calif., assignor to Chevron Research Company,San Francisco, Calif., a corporation of Delaware Filed May 6, 1966, Ser.No. 548,258 1 Claim. (Cl. 208-111) ABSTRACT OF THE DISCLOSUREHydrocracking hydrocarbon feeds boiling above 900 F. to produce lighthydrocarbon gases, C -C in a yield of at least weight percent, using aGroup VIII hydrogenating metal component associated with a crystallinezeolitic aluminosilicate.

The present invention relates to a process for the conversion of heavyhydrocarbon fractions to light hydrocarbon gases of one to four carbonatoms. More particularly, the present invention is concerned with thehydrocracking of hydrocarbon feeds, a substantial portion of which boilsabove 900 F., to light hydrocarbon gases of one to four carbon atoms,and especially three to four carbon atoms, the hydrocracking beingaccomplished in the presence of a catalyst comprising a zeoliticaluminosilicate and a hydrogenating metal component.

The light hydrocarbon gases of one to four carbon atoms have generallybeen synthesized as a by-product from the catalytic cracking andhydrocracking of hydrocarbon oils to obtain gasolines and higher boilingproducts. Although the light gases produced are usually only a fewweight percent of the hydrocarbon feed cracked, they are very valuable,especially the gases containing three to four carbon atoms which aresold as liquefied petroleum gases or LPG for use as chemical rawmaterials and household fuels. Because of the increasing demand forlight hydrocarbon gases, it would be valuable to have a process forproducing light gases in higher yields than generally obtainable as aby-product in the production of gasoline. Moreover, since lighthydrocarbon gases of one to four carbon atoms are generally produced atthe expense of gasoline, it would be particularly valuable to have aprocess for hydrocracking high boiling feeds, which feeds are difficultto refine and hence are less valuable for gasoline production, directlyto light hydrocarbon gases as a principal reaction product.

In accordance with the present invention, high boiling hydrocarbonfeeds, at least a substantial portion of which boils above 900 F., canbe converted directly to large quantities of light hydrocarbon gases ofone to four carbon atoms as a principal reaction product by contactingsaid feed and hydrogen in a reaction Zone under hydrocracking conditionswith a catalyst comprising a crystalline zeolitic aluminosilicatecharacterized by uniform pores of at least 6 A. and having ahydrogenating metal component intimately associated therewith, saidcontacting being at a relatively high temperature and at conditionssufficient to convert substantially all of said feed to products boilingbelow 900 F.

As illustrated hereinbelow, the present process is to be contrasted toprior hydrocracking processes which are mainly concerned with theproduction of high yields of gasoline and middle distillates and minimumproduction of light gases. The present process is particularly directedto obtaining high yields of light gases from high boiling petroleumfeeds which are diflicult to convert to gasoline and other high qualityfuel products.

The light gases produced, particularly the hydrocarbons 3,385,782Patented May 28, 1968 ice of three to four atoms (C -C apart from beinguseful for LPG production, can be used in dehydrocyclodimerizationreactions to produce higher molecular weight aromatic hydrocarbons.

The present invention may be understood and will be further explainedwith reference to the figure which is a graph comparing the conversionto light hydrocarbon gases as a function of hydrocracking temperaturefor a palladium containing zeolitic aluminosilicate catalyst and anothercatalyst.

Hydrocarbon feeds boiling above 900 F. are generally difiicult toconvert to more useful lower boiling products. Hence it is considered apart of the present invention to use hydrocarbon feeds, a substantialamount of which boils above 900 F. and preferably hydrocarbon feeds atleast of which boils above 900 F. It is understood, however, that thepresent invention may be used wherein less than 85% of the feed boilsabove 900 F. However, at least 50% of the feed should boil above 900 F.in order to realize the benefits of the present invention. Feedstockswhich may be used in the hydrocracking process of the present inventioninclude heavy virgin crudes, vacuum distillation residues, heavycatalytic cycle oils, and gas oils resulting from visbreaking of heavyoils. Particularly preferred feedstocks are solvent deasphalted oils,such as propane deasphalted oils, which boil in the desired temperaturerange. The hydrocarbon fractions may be derived from petroleum crudeoils, shale oils, tar sand oils, coal hydrogenation or carbonizationproducts and the like.

For purposes of the present hydrocracking process, it is not considerednecessary to purify the hydrocarbon feeds of nitrogen and sulfurcompounds. It has been found that the present invention workssatisfactorily with feeds containing high nitrogen content, as, forexample, feeds containing a nitrogen content above 5000 p.p.m. Thus itis a particular advantage of the present process that the hydrocarbonfeeds do not require hydrofining operations, and in particularhydrodenitrification or hydrodesulfurization processes, prior to thehydrocracking step. It is understood, however, that hydrofining can beused in conjunction with the hydrocracking process if desired.

The crystalline zeolitic aluminosilicates encompassed by the presentinvention comprise open three-dimensional crystalline networks ofalumina and silica tetrahedra, which tetrahedra are intimately connectedwith each other by the sharing of oxygen atoms. In the hydrated form thealuminosilicates can be represented by the basic formula:

wherein M is a cation which balances the negative electrovalence of thetetrahedra; n represents the valence of the cation; w, the moles of SiOand y, the moles of water. The cation, M, may be any of a number ofions, such as, for example, the alkali metal ions, and the alkalineearth ions. The cations may be mono-, di-, or trivalent. In general aparticular type of crystalline zeolitic aluminosilicate will have valuesfor w and y that fall in a definite range. The zeolitic cations, e.g.alkali metal or alkaline earth metal cations, may be replaced one withanother by suitable exchange techniques. Consequently, crystallinezeolitic aluminosilicates are often employed as ion-exchange agents. Thereplacement of the zeolitic cations with other cations, .as, forexample, the replacement of sodium cations with calcium cations,generally does not induce appreciable changes in the anionic framework.

The crystal structures of many zeolitic aluminosilicates exhibitinterstices of molecular dimensions, which interstices are generallyoccupied by water of hydration. Dehydration results in a relatively opensystem of channels wherein foreign molecules may be adsorbed. Access tothese channels is had by way of apertures in the crystal lattice, whicheffectively, then, limit the size and shape of molecules that can beadsorbed. Separation of mixtures of foreign molecules based on moleculardimensions is thus possible, and it is this characteristic property ofmany zeolitic aluminosilicates that has led to their designation asmolecular sieves.

Both the natural and synthetic zeolitic aluminosilicates maybe used inthe present invention. The aluminosilicates which find use for purposesof this invention possess relatively well-defined pore structures. Theexact type of aluminosilicates is relatively unimportant as long as thepore structures comprise openings characterized by pore dimensionsgreater than 6 A., and in particular uniform pore diameters of between 6and A. It is necessary that the uniform pore dimensions are larger thanapproximately 6 A. in order to permit the hydrocarbons to behydrocracked to gain access to reactive sites of the catalyst.Generally, in order to obtain aluminosilicates of the necessary porediameters the silica to alumina mole ratio in the crystalline formshould be greater than about 2. Suitable zeolitic aluminosilicates whichmay be used in the present process are the natural faujasites;synthesized zeolite X which is described in US. Patent 2,882,244; andsynthetized zeolite Y which is described in US. Patent 3,130,007.Zeolite Y is preferable because of its greater commercial availabilityand its greater stability.

The procedures for the preparation of synthetic crystalline zeoliticaluminosilicates are well known in the art. For example, theseprocedures generally involve the mixing and heating of a high silica/alumina mole ratio mixture of sodium silicate and sodium aluminate.Thereagents are mixed under carefully controlled conditions to produce acrystalline product which contains sodium as the zeolitic cations. Thesodium zeolitic cations can be subsequently ion-exchanged with otherdesirable cations.

The catalyst encompassed for use in the present process comprises azeolitic aluminosilicate having intimately associated therewith ahydrogenating metal component. Suitable hydrogenating metal componentsfor use in this invention are the metals, and compounds thereof, ofGroups VI, VII, and VIII of the Periodic Table. However, the Group VIIIhydrogenating metals, and compounds thereof, are preferred. Thehydrogenating metal component can be in the form of elemental metal orits compounds, as, for example, the oxide or sulfide form. Although theoxides and sulfides are the preferred compound forms of the metalhydrogenating component, any compound which performs as a hydrogenatingcomponent may be used in the catalyst for purposes of this invention.The amount of hydrogenating metal component intimately associated withthe zeolitic aluminosilicates can vary from 0.1 to weight percentcalculated as the metal, but preferably will be in the range 0.5 to 10weight percent. It is understood, of course, that mixtures of two ormore metals or compounds may be intimately associated with thealuminosilicate.

The catalytically active hydrogenating metal component can be introducedinto the crystalline aluminosilicate by any method which results in ahighly dispersed catalytically active metal. Suitable methods which canbe employed are impregnation and ion-exchange. Generally, in preparingthe catalyst by impregnation, a zeolitic aluminosilicate is mixed withan aqueous solution of a decom-j posable metal compound, the metalcompound being in an amount sufficient to contain the quantity of metaldesired in the finally prepared catalyst product. The aluminosilicate isthen dried and heated to a temperature sufficient to thoroughly removethe water. Further heating may be necessary to decompose the metalcompound. Impregnation may also be accomplished by adsorption of a fluiddecomposable compound of the metal, followed by decomposition of themetal compound. Ion-exchange can be satisfactorily accomplished bycontacting the aluminosilicate with an aqueous solution of a suitablemetal salt for sufiicient time to replace the zeolitic cations with themetal cations and then drying to remove water. Ionexchange may alsooccur with an aqueous solution containing a cationic metal complexfollowed by decomposition of the complex.

The metal component, whether incorporated into the crystal lattice byion exchange or impregnation, can be chemically reduced to the elementalform by contact with a reducing atmosphere such as hydrogen. The reducedform of the metal can then be converted to an oxide or sulfide form, ifdesired, by contacting the metal containing aluminosilicate with, forexample, an oxygen-containing or sulfur-containing atmosphere,respectively. Sulfiding is preferably performed by contacting thecatalyst containing the hydrogenating metal component with asulfur-containing hydrocarbon feed.

The zeolitic aluminosilicate containing a hydrogenating metal componentcan be mixed with other catalytic materials and used in thehydrocracking process of the present invention. For example, thealuminosilicate containing a hydrogenating metal component may be mixedwith a silica-alumina type catalyst. Other suitable catalytic materialsinclude silica-boria, silica-magnesia, and alumina. The crystallinezeolitic aluminosilicate containing a hydrogenating metal component canalso be mixed with suitable support materials such as the clays toobtain beneficial property such as high attrition resistance and highcompactibility. The physical form of the catalyst will vary with themanipulative process to which it may be exposed. Thus the presenthydrocracking process can be carried out by maintaining the catalyst ina fluidized bed, in which case the catalyst will be in a powdered form;or, the present process can consist of a moving bed or fixed bed inwhich case the catalyst can be in the form of beads, tablets or extrudedpellets.

The conditions of temperature, pressure, hydrogen fiow rate, and liquidhourly space velocity in the reactor are correlated to provide thedegree of hydrocracking required to convert substantially all (i.e.,above by weight, and, preferably above the feed boiling above 900 F. toproducts boiling below that temperature. Generally, the higher theboiling range of the feed, the higher the temperature, pressure and/orhydrogen flow rate necessary to convert the feed to products boilingbelow 900 F. Under properly selected conditions, light hydrocarbon gasescan be produced as a principal reaction product, that is, preferably ina yield of at least 25 weight percent and more preferably 50 weightpercent.

For the purposes of the present invention, the temperature is preferablymaintained at least 10 F. above the minimum temperature at which thefeed is substantially completely converted (i.e., above 90%) to productsboiling below 900 F. In general, the temperature in the reaction zonefor hydrocracking feedstocks in accordance with the present invention isat least 750 F., and more preferably at least 800 F. For higher boilingfeedstocks, the hydrocracking temperature will in general be higher.Thus for feedstocks at least 85% of which boils above 900 F., thepreferred temperature in the reaction zone is at least 800 F. andpreferably at least 830 F. Ordinarily, it will not be necessary to goabove a temperature of 950 F. Thus, substantially complete conversion ofthe feed to light hydrocarbon gases can generally be achieved at atemperature below 950 F. It is understood, however, that the temperatureis only one of the hydrocracking conditions to control the yield oflight gases produced.

The pressure advantageously influences the rate of hydrocracking as wellas the extent of hydrocracking. Furthermore the pressure has the effectof influencing the catalyst activity and life, elevated pressuresextending the life and activity of the catalyst. Generally, pressuresbetween 1000 to 10,000 p.s.i.g. are used in the hydocracking process ofthe present invention, the higher pressures being used with the higherboiling feedstocks. Preferably, pressures between 2000-6000 p.s.i.g. areused.

The hydrogen flow rate into the reactor is maintained betweenapproximately 1,000 to 20,000 s.c.f./bbl. of feed and preferably in therange 4,000 to 10,000 s.c.f./bbl. Generally, at least sufficienthydrogen is provided to supply that consumed in the cracking of highmolecular weight hydrocarbons to light hydrocarbon gases and thatconsumed in the conversion of the nitrogen compounds to ammonia and anyincidental hydrogenation of unsaturates and oxygen and sulfur compounds,while mai taining a significant hydrogen partial pressure. The hy-drogenconsumption will generally vary from 1,000 to 10,000 s.c.f./bb1. of feeddepending on the properties of the hydrocarbon feed and the otherhydrocracking conditions used. Excess hydrogen is separated from thetreated feed, and preferably purified and recycled. The use of morehydrogen than 20,000 s.c.f./bbl. of feed does not generally providesufficient improvement to justify the increased cost of circulating it.

The liquid hourly space velocity (LHSV), that is, the flow ofhydrocarbon feed relative to the catalyst, will generally be in therange 0.1-10 but preferably 0.3-5. The higher boiling the feed, thelower the space velocity. For example, a space velocity of 2 isadvantageously used with a feed at least 50% of which boils above 900F., while a space velocity of 0.5 is advantageously used with a feed atleast 85% of which boils above 900 F.

The present invention may be more fully understood by reference to thefollowing examples. In these examples since product distribution did notchange appreciably after about one day of operation, the determinationsof product distribution were made a-t any time after one day.

Example 1 A crystalline zeolitic aluminosilicate of the Y crystal typehaving intimately associated therewith a hydrogenat- 6 least about 85 ofthe feed boiled above 900 F. The principal characteristics of the feedwere:

Gravity, API 16.2 Aniline point, F. 192.0 Total nitrogen content, p.p.m.5950 Feed distillation range, wt. percent, R:

The high boiling hydrocarbon feed was contacted with the palladiumcontaining aluminosilicate catalyst under hydrocracking conditionsincluding a pressure of approximately 2400 p.s.i.g., a hydrogen flowrate into the reaction zone of approximately 6,000 s.c.f./bbl. of feedand a liquid hourly space velocity of 0.5. The hydrocracking process wasconducted at various temperatures. The hydrocracking conditions andproduct distribution are presented in Table I. For comparison, acatalyst was selected as representative of the effect most conventionalhydrocracking catalysts would have on light hydrocarbon gas production.This catalyst is very effective for converting heavy feeds to lowerboiling products including gasoline and other middle distillate fuels.The comparison catalyst was composed of nickel and tungstenhydrogenating components associated with an active cracking supportcomposed of mixed refractory oxides which were mainly alumina andsilica; the catalyst did not contain any zeolitic aluminosilicate. TableI shows, for comparative purposes, the results obtained when thecomparison catalyst was used for hydrocracking the propane deasphaltedoil described above under conditions substantially the same as above.The amount of hydrogen not consumed in the hydrocracking process wasmeasured and is recorded as hydrogen flow rate out.

TABLE I Reaction Conditions Product Distribution, Weight PercentCatalyst Temp, Press, H2 Rate F. p.s.i.g. LHSV Out, C1-C2 C3-C4 (ls-400F. 400650 F. GET-900 I 900 F.+

s.e.f./bbl.

805 2,400 0 5 4,890 1.0 4.1 13.4 14.3 23.8 43 PalladiumA1uminosilicate.. 830 2, 400 0.5 3. 7 11 21 9 855 2, 400 0. 5 2, 580 8.2 46. 9 43 0. 6 1.0 0 Comparison Catalyst 805 2, 360 0.5 5, 280 1. 8 3.2 29 35 23 8 850 2,460 0 5 3, 770 6.1 6.0 67 19 0 0 ing palladiumcomponent was prepared by contacting an ammonium aluminosilicate with anammonium hydroxide solution containing palladium chloride, saidpalladium chloride being in suflicient quantity to permit 1.2% palladiumto be deposited on the final catalyst preparation. The mixture wasallowed to stand overnight, after which the excess solution was washedaway with water. The ammonium aluminosilicate containing palladium wasthen dried at a temperature of 250 F. for sufficient time to remove mostof the water and then calcined at 1000 F. The resulting hydrogen form ofthe sieve containing palladium as the hydrogenating metal component wastreated at 1000 F. in a wet hydrogen atmosphere for a sufficient timetoactivate the catalyst for hydrocracking reactions. The catalyst wasthen sulfided at 600 F. in a hydrogen and dimethyldisulfide atmosphere.

The deasphalted oil obtained by subjecting residuum from the vacuumdistilling of petroleum crude to a propane deasphalting treatment, wasused as the feedstock for the hydrocracking process using the abovedescribed palladium containing zeolitic .aluminosilicate catalyst. At

The percent conversion to light gaseous products containing one to fourcarbon atoms as well as the percent conversion to light gaseous productscontaining three to four carbon atoms at different hydrocrackingtemperatures for the two catalysts are presented in graphical form inthe figure. The total hydrocracking conversion to products boiling below900 F. (total conversion to 900 F.-) was measured as a function ofhydrocracking temperature and is also presented in the figure.

Curves A and B in the figure illustrate that the comparisonhydrocracking catalyst gave higher total conversion to products boilingbelow 900 F. than the zeolitic aluminosilicate catalyst at anyparticular temperature. Curves C and D indicate that the comparisonhydrocracking catalyst gave a product of light hydrocarbon gases whichincreased only slightly as the hydrocracking temperature was increasedabove 800 F. It was heretofore considered that the effect of zeoliticaluminosilicates on the production of light gases would follow the sametrend as the effect with the comparison catalyst and with mostconventional hydrocracking catalysts; that is to say, that theproduction of light hydrocarbon gases in a hydrocracking process using azeolitic aluminosilicate catalyst would increase only gradually as thehydrocracking temperature was increased. In contrast thereto theproduction of light hydrocarbon gases when using the zeoliticaluminosilicate catalyst in accordance with the present invention wassignificantly and dramatically increased, as shown by curves E and F inthe figure. Thus by conducting the hydrocracking process with the abovezeolitic aluminosilicate catalyst at a temperature and under conditionssufiicient to convert substantially all of the feed to products boilingbelow 900 F., light hydrocarbon gases can be produced as a principalreaction product. In this particular example, the feed was substantiallycompletely converted (i.e., 90%) to products boiling below 900 F. at atemperature of about 830 F. and above this temperature the lighthydrocarbon gas yield increased rapidly.

Referring now to Table I, it is noted that using a palladium-zeoliticaluminosilicate catalyst and under hydrocracking conditions, including atemperature of 855 F. whereby high gas yields were produced, that theremaining product consisted predominantly of gasoline. Thus a specialbenefit of the present process is that under conditions adapted to yieldlight gases as a principal reaction product, the remaining eflluent orproduct from the reactor will be exceptionally high in gasoline content.For example, when light hydrocarbon gases are produced in yields ofabout 50% by weight of the total product, the remaining product willcomprise essentially gasoline.

Example 2 A nickel containing zeolitic aluminosilicate catalyst wasprepared by exchanging approximately 6.3% nickel onto an ammoniumaluminosilicate (type Y). The resulting catalyst, after proper dryingand calcination treatment, was sulfided at 600 F. in a hydrogen anddimethyldisulfide atmosphere. The catalyst was used in a hydrocrackingprocess employing a feed having the following principal characteristics:

Gravity, API 14.7 Aniline point, F. 166.0 Total nitrogen content, p.p.m.8300 Feed distillation range, wt. percent, R:

The hydrocracking reaction conditions as well a the product distributionat two temperatures are given in Table II.

The results from hydrocracking of a high boiling feed with a nickelaluminosilicate catalyst are similar to the results obtained with thepalladium aluminosilicate. The high gas yields produced at 850 F. wereobtained above the temperature at which substantially all the feed wasconverted to products boiling below 900 F. It is apparent that rapidincrease in gas yield was obtained in raising the temperature from 822to 850 F.

Example 3 A catalyst comprising a zeolitic aluminosilicate of the Ycrystal type and having intimately associated therewith 16% nickel, wasused in the hydrocracking of the hydrocarbon feed described in Example2. The catalyst was sulfided as in the previous examples prior to use.The product distribution and run conditions are presented in Table III.The hydrogen added to the reactor (H Rate In) and the hydrogen removed(H Rate Out), both measured in terms of standard cubic feet per barrelof feed are also presented in Table III. Exceptionally high gas yieldswere obtained. Note that the feed has been converted to products boilingbelow 900 F.

TABLE III Catalyst: Nickel aluminosilicate. Reaction conditions:

Temp, F. 850 Pressure, p.s.i.g 2350 LHSV 0.5 H rate in, s.f.c./bbl 6540H rate out, s.c.f./bbl 2510 H consumed, s.c.f./bbl. 4030 Productdistribution, wt. percent:

C -C 10.5 C -C 53.0 C -400 F. 34.0 400-650 F. 0 650-900 F. 0

EXAMPLE 4 Hydrocracking of the high boiling feed described in Example 2was performed using a decationized zeolitic aluminosilicate containingno hydrogenating metal component. The reaction conditions and productdistribution are shown in Table IV.

TABLE IV Catalyst: Decationized aluminosilicate. Reaction conditions:

Temp, F. 857 Pressure, p.s.i.g 2360 LHSV 0.5 H rate in, s.c.f./bbi 4900H rate out, s.c.f./bbl 3540 H consumed, s.c.f./bbl. 1360 Productdistribution, wt. percent:

C -C 8.7 C -C 10.3 C -400" F. 37.0 400-650 F. 30.0 650-900 F. 12.0 900F.+ 1.2

Although the feed was substantially converted to products boiling below900 F., the production of light gases (C -C was low. The yield of lighthydrocarbon gases of one to four carbon atoms was considerably lowerthan yields obtained with an aluminosilicate catalyst containing ahydrogenating metal component. It is apparent that in order to obtainhigh yields of light hydrocarbon gases, the feed must be contacted, inthe presence of hydrogen, with a catalyst comprising a zeoliticaluminosilicate and having intimately associated therewith ahydrogenating metal component.

The light hydrocarbon gases produced by the process of the presentinvention can be subsequently subjected to steam reforming or partialoxidation to produce a hydrogen-rich or methane-rich product for use asan ingredient in fuel gas, e.g., town gas. Because town gas comprises,predominantly, hydrogen, and a hydrocarbon or mixture of hydrocarbons(mainly methane or methane and ethane), it is contemplated that thelight hydrocarbons produced in the present process can be separated intotwo fractions, a first fraction comprising essentially the hydrocarbonsof one to two carbon atoms, and a second fraction com-prising thehydrocarbons of three to four carbon atoms; then using said firstfraction as an ingredient of town ga and subjecting said second fractionto steam reforming or partial oxidation for conversion to hydrogenand/or methane. Alternatively, the entire light hydrocarbon gases can beused as a fuel gas enrichment material for a hydrogen-rich gas producedin a steam reforming process or other suitable gasification process.

The gasoline produced along with the light hydrocarbon gases can also besubjected to various gasification processes, e.g., steam reforming,thermal hydrocracking, or partial oxidation, to yield a hydrogen-rich ormethanerich gas for use as a fuel gas. Generally, however, the gasolinefraction, which has been found to be highly aromatic, will be used as amotor fuel.

I claim:

1. A process for the conversion of a heavy hydrocarbon feed, at least 85weight percent of which boils above 900 F., to light hydrocarbon gasesof l to 4 carbon atoms in a yield of at least 25 Weight percent as aprincipal reaction product Which comprises contacting said feed andhydrogen in a reaction zone With a catalyst comprising a crystallinezeolitic aluminosilicate of the Y crystal type characterized by uniformpores from 6 to 15 Angstroms and having intimately associated therewitha Group VIII hydrogenating metal component, at hydrocracking conditionsincluding a temperature above about 830 F., a pressure between about2000 to 6000 p.s.i.g., and a liquid hourly space velocity of from 0.1 to10, converting above 90 weight percent of the feed per pass to productsboiling below 900 F., and recovering said light hydrocarbon gases.

References Cited UNITED STATES PATENTS ABRAHAM RIMENS, Primary Examiner.

